Masters Theses

Russ Manning

Date of Award

8-1981

Degree Type

Thesis

Degree Name

Master of Arts

Major

Philosophy

Major Professor

Sheldon Reaven

Committee Members

H. Phillips Hamlin

Abstract

The purpose of this study was to explicate the current status of the diversity-stability hypothesis in ecology—the proposition that species diversity increases population stability. The historical and philosophical background was explored to show that the hypothesis, rather than being founded on solid scientific evidence, is more a part of our "folk science" and was readily accepted because it fit our predisposition for order and purpose in nature and satisfied our aesthetic evaluation of species diversity. But the classical argument for the diversity-stability hypothesis was shown to be inadequate; in fact, a necessary and sufficient causal relationship was shown to be false.

With diversity defined as species number, plus a measure of species interconnectedness and correct proportions, and stability defined as the ability to return to and maintain a base state, an alternative hypothesis was proposed: Diversity and stability are associated in the presence of a third factor, environmental favorability. But it was also argued that if diversity increases stability within this context, it does so only up to some level of specialization, beyond which overspecialization destabilizes the system. Support for this alternative was qualified in that it was thought that this is but one hypothesis from among many that should be put forward in order to increase the research options.

Since the alternative hypothesis stated that diversity increases stability only within a certain range of specialization and only within the context of environmental favorability, it was suggested that a universal law about diversity-stability may not be possible and that this condition is characteristic of the science of biology itself and not just diversity-stability relationships. The complexity of living organisms and their interrelationships was proposed as the factor that prevents the formulation of universal laws in biology.

It was concluded that whatever the relationship between diversity and stability, it must exist within the context of many environmental and biological factors. Because of the present ambiguity, a case was made for the exercise of caution in the management and exploitation of our natural resources along with preservation of representative ecosystems.

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